Lots of good stuff but I could tell anyone to learn to do something healthy that they enjoy that goes beyond the confines or restrictions of something organized for you like school, etc.; Playing/learning musical instruments, running/biking/lifetime exercises, camping, gardening, whatever.
-Live by yourself for a long stretch of time. Self sufficiency is a big deal. Along with that, do things by yourself; travel, camp, go to concerts, the empty bar in the afternoon. You can learn a lot about yourself and maybe others too.
-work jobs that lots of other people won't do; bussing/serving tables, stocking shelves at a store, etc. They're good for a back up/side hustle and help develop different skills and an appreciation for how those little 'mini-works' work.
-It's not to be selfish but ALWAYS take care of yourself first and foremost. You can keep yourself steady which makes it easier for when you do need to take care of someone else.